Tendon sheath cysts in 3-year-olds are a common condition that is usually not serious and can return to normal with medically prescribed treatment.
Tendon sheath cysts are cystic swellings formed due to repeated friction between the tendon and the tendon sheath and increased exudation of synovial fluid, which is a benign lesion. If detected early, the wall of the cyst can be broken by squeezing, so that the synovial fluid can penetrate into the tissue space to achieve healing, but there is a certain chance of recurrence.
If the cyst is large and the wall is thick, it can also be treated by surgery, such as tenosynovial cystectomy, to remove the wall of the cyst, and there is usually no after-effects.
To summarize, if a 3-year-old child has a tendon sheath cyst, there is no need to worry too much, and should consult a doctor in time.